java實現紅/黑樹狀結構

           紅/黑樹狀結構是一種經典的資料結構，在linux記憶體管理、nginx 等很多地方用到它。主要操作包括插入、刪除，其中插入6種情況，刪除8種情況，詳細的思路就不說了，如果不太明白的請參考演算法導論13章，看的時候一定要把每一種插入、刪除的情況在紙上自己畫出來，這樣會節省你很多時間。下面是java實現的代碼：

package com.algorithm.rbtree;public class RBTree {private final Node NIL = new Node(null,null,null,Color.BLACK,-1);private Node root;public RBTree() {root = NIL;}public RBTree(Node  root) {this.root = root;}//插入節點public void rbInsert(Node node) {Node previous = NIL;Node temp = root;while (temp != NIL) {previous = temp;if (temp.getValue() < node.getValue()) {temp = temp.getRight();} else {temp = temp.getLeft();}}node.setParent(previous);if (previous == NIL) {root = node;root.setParent(NIL);} else  if (previous.getValue() > node.getValue()) {previous.setLeft(node);} else {previous.setRight(node);}node.setLeft(NIL);node.setRight(NIL);node.setColor(Color.RED);rb_Insert_Fixup(node);}//插入節點後的調整private void rb_Insert_Fixup(Node node) {while (node.getParent().getColor() == Color.RED) {if (node.getParent() == node.getParent().getParent().getLeft()) {Node rightNuncle = node.getParent().getParent().getRight();if (rightNuncle.getColor() == Color.RED) {         //Case 1rightNuncle.setColor(Color.BLACK);node.getParent().setColor(Color.BLACK);node.getParent().getParent().setColor(Color.RED);node = node.getParent().getParent();} else if (node == node.getParent().getRight()) {  //case 2node = node.getParent();leftRotate(node);} else {                                          //case 3node.getParent().setColor(Color.BLACK);node.getParent().getParent().setColor(Color.RED);rightRotate(node.getParent().getParent());}} else {Node leftNuncle = node.getParent().getParent().getLeft();if (leftNuncle.getColor() == Color.RED) {     //case 4leftNuncle.setColor(Color.BLACK);node.getParent().setColor(Color.BLACK);node.getParent().getParent().setColor(Color.RED);node = node.getParent().getParent();} else if (node == node.getParent().getLeft()) { //case 5node = node.getParent();rightRotate(node);} else {                                          // case 6node.getParent().setColor(Color.BLACK);node.getParent().getParent().setColor(Color.RED);leftRotate(node.getParent().getParent());}}}root.setColor(Color.BLACK);}//刪除節點public Node rbDelete(int data) {Node node = search(data);Node temp = NIL;Node child = NIL;if (node == null) {return null;} else {if (node.getLeft() == NIL || node.getRight() == NIL) {temp = node;} else {temp = successor(node);}if (temp.getLeft() != NIL) {child = temp.getLeft();} else {child = temp.getRight();}child.setParent(temp.getParent());if (temp.getParent() == NIL) {root = child;} else if (temp == temp.getParent().getLeft()) {temp.getParent().setLeft(child);} else {temp.getParent().setRight(child);}if (temp != node) {node.setValue(temp.getValue());}if (temp.getColor() == Color.BLACK) {rb_Delete_Fixup(child);}return temp;}}//刪除節點後的調整private void rb_Delete_Fixup(Node node) {while (node != root && node.getColor() == Color.BLACK) {if (node == node.getParent().getLeft()) {Node rightBrother = node.getParent().getRight();if (rightBrother.getColor() == Color.RED) {          //case 1 node節點為左孩子，node節點的兄弟為REDrightBrother.setColor(Color.BLACK);node.getParent().setColor(Color.RED);leftRotate(node.getParent());rightBrother = node.getParent().getRight();}if (rightBrother.getLeft().getColor() == Color.BLACK && rightBrother.getRight().getColor() == Color.BLACK) {rightBrother.setColor(Color.RED);node = node.getParent();} else if (rightBrother.getRight().getColor() == Color.BLACK) {rightBrother.getLeft().setColor(Color.BLACK);rightBrother.setColor(Color.RED);rightRotate(rightBrother);rightBrother = node.getParent().getRight();} else {rightBrother.setColor(node.getParent().getColor());node.getParent().setColor(Color.BLACK);rightBrother.getRight().setColor(Color.BLACK);leftRotate(node.getParent());node = root;}} else {Node leftBrother = node.getParent().getLeft();if (leftBrother.getColor() == Color.RED) {leftBrother.setColor(Color.BLACK);node.getParent().setColor(Color.RED);rightRotate(node.getParent());leftBrother = node.getParent().getLeft();} if (leftBrother.getLeft().getColor() == Color.BLACK && leftBrother.getRight().getColor() == Color.BLACK) {leftBrother.setColor(Color.RED);node = node.getParent();} else if (leftBrother.getLeft().getColor() == Color.BLACK) {leftBrother.setColor(Color.RED);leftBrother.getRight().setColor(Color.BLACK);leftRotate(leftBrother);leftBrother = node.getParent().getLeft();} else {leftBrother.setColor(node.getParent().getColor());node.getParent().setColor(Color.BLACK);leftBrother.getLeft().setColor(Color.BLACK);rightRotate(node.getParent());node = root;}}}node.setColor(Color.BLACK);}//尋找節點node的後繼節點public Node successor(Node node) {Node rightChild = node.getRight();if  (rightChild != NIL) {Node previous = null;while (rightChild != NIL) {previous = rightChild;rightChild = rightChild.getLeft();}return previous;} else {Node parent = node.getParent();while (parent != NIL && node != parent.getLeft()) {node = parent;parent = parent.getParent();}return parent;}}//尋找節點public Node search(int data) {Node temp = root;while (temp != NIL) {if (temp.getValue() == data) {return temp;} else  if (data < temp.getValue()) {temp = temp.getLeft();} else {temp = temp.getRight();}}return null;}//左轉函數private void leftRotate(Node node) {Node rightNode = node.getRight();node.setRight(rightNode.getLeft());if (rightNode.getLeft() != NIL) {rightNode.getLeft().setParent(node);}rightNode.setParent(node.getParent());if (node.getParent() == NIL) {rightNode = root;} else if (node == node.getParent().getLeft()) {node.getParent().setLeft(rightNode);} else {node.getParent().setRight(rightNode);}rightNode.setLeft(node);node.setParent(rightNode);}//右轉函數private void rightRotate(Node node) {Node leftNode = node.getLeft();node.setLeft(leftNode.getRight());if (leftNode.getRight() != null) {leftNode.getRight().setParent(node);}leftNode.setParent(node.getParent());if (node.getParent() == NIL) {root = leftNode;} else if (node == node.getParent().getLeft()) {node.getParent().setLeft(leftNode);} else {node.getParent().setRight(leftNode);}leftNode.setRight(node);node.setParent(leftNode);}//中序遍曆紅/黑樹狀結構public void printTree() {inOrderTraverse(root);}private void inOrderTraverse(Node node) {if (node != NIL) {inOrderTraverse(node.getLeft());System.out.println(" 節點："+node.getValue() + "的顏色為：" + node.getColor());inOrderTraverse(node.getRight());}}public Node getNIL() {return NIL;}}class Node {private Node left;private Node right;private Node parent;private Color color;private int value;public Node(Node left, Node right, Node parent, Color color, int value) {super();this.left = left;this.right = right;this.parent = parent;this.color = color;this.value = value;}public Node() {}public Node(int value) {this(null,null,null,null,value);}public Node getLeft() {return left;}public void setLeft(Node left) {this.left = left;}public Node getRight() {return right;}public void setRight(Node right) {this.right = right;}public Node getParent() {return parent;}public void setParent(Node parent) {this.parent = parent;}public Color getColor() {return color;}public void setColor(Color color) {this.color = color;}public int getValue() {return value;}public void setValue(int value) {this.value = value;}}enum Color {RED,BLACK}

下面是測試代碼：

package com.algorithm.rbtree;public class RBTreeTest {/** * @param args */public static void main(String[] args) {RBTree rbTree = new RBTree();rbTree.rbInsert(new Node(41));rbTree.rbInsert(new Node(38));rbTree.rbInsert(new Node(31));rbTree.rbInsert(new Node(12));rbTree.rbInsert(new Node(19));rbTree.rbInsert(new Node(8));//rbTree.printTree();rbTree.rbDelete(19);rbTree.printTree();}}